This now seems to be making sense to me, so please correct me if I'm wrong:

A successful system call yields the bash exit code of "0", and the Perl interpretation of this "0" (as being a failure), permits execution of the "other" component of the || comparison operator.

On the other hand, an unsuccessful system call produces an exit code other than "0", and is erroneously interpreted by Perl as "true". This accounts for Perl's action of allowing an unsuccessful system call to stand in as true for the first component of the "&&" operator.

Please excuse me if this comes across as a lame discussion, but this issue has been difficult for me to understand.

Thanks!